In this comment two assertions concerning a regular pair of crisp matr
oids are presented in order to clarify an important step of the proof
of Lemma 2.5 of the paper by Goetschel and Voxman. One of these assert
ions provides an independent proof of Lemma 2.4 of the paper by Goetsc
hel and Voxman as well. (C) 1997 Elsevier Science B.V.